Zoom lens and image pickup apparatus including the same
A zoom lens includes, in order from object side: a positive first unit not moving for zooming; a second unit moving during zooming; a positive third unit; a positive fourth unit; and a rear unit including at least one unit, the second unit including one or more lens sub-units and having a negative refractive power as a whole, the fourth unit moving during zooming, the zoom lens including a stop between the second and third units or between the third and fourth units. Lateral magnifications of the second unit at a wide angle end and a telephoto end when beam enters from infinity, focal lengths at the wide angle end and the telephoto end, a focal length of the first unit, and a focal length of the second unit at the wide angle end are appropriately set.
1. A zoom lens comprising in order from an object side to an image side: a first lens unit having a positive refractive power; a second lens unit; a third lens unit having a positive refractive power; a fourth lens unit having a positive refractive power; and a rear lens unit including at least one lens unit, wherein
the second lens unit includes one or more lens sub-units, and has a negative refractive power as a whole,
the first lens unit does not move for zooming, the second lens unit moves during zooming, the fourth lens unit moves during zooming,
the zoom lens includes a stop between the second lens unit and the third lens unit or between the third lens unit and the fourth lens unit, and
the zoom lens satisfies the following expressions:
0.50<( ft ×β2 w 2 )/( fw ×β2 t 2 )<1.40 and
−2.45< f 1/ f 2<−0.50,
where β2w and β2t respectively represent lateral magnifications of the second lens unit at a wide angle end and a telephoto end when a light beam enters from infinity, fw and ft respectively represent focal lengths of the zoom lens at the wide angle end and the telephoto end, f1 represents a focal length of the first lens unit, and f2 represents a focal length of the second lens unit at the wide angle end.
2. A zoom lens according to claim 1 , wherein the stop is configured not to move in an optical axis direction for zooming.
3. A zoom lens according to claim 1 , wherein the third lens unit and the fourth lens unit are configured to move during zooming, and satisfy the following expression:
0.40< f 3/ f 4<2.50,
where f3 and f4 respectively represent focal lengths of the third lens unit and the fourth lens unit.
4. A zoom lens according to claim 3 , wherein the following expression is satisfied:
0.01< L 34 t/L 34 w< 0.60,
where L34w and L34t respectively represent intervals between the third lens unit and the fourth lens unit at the wide angle end and the telephoto end.
5. A zoom lens according to claim 1 , wherein the rear lens unit is configured not to move for zooming.
6. A zoom lens according to claim 1 , wherein the first lens unit comprises in order from the object side to the image side: a first lens sub-unit having a negative refractive power, which is configured not to move for focusing; a second lens sub-unit having a positive refractive power, which is configured to move during focusing; and a third lens sub-unit having a positive refractive power, and satisfies the following expression:
−1.5< f 11/ f 1<−0.4,
where f11 represents a focal length of the first lens sub-unit.
7. A zoom lens according to claim 1 , wherein the rear lens unit comprises three or more lenses.
8. A zoom lens according to claim 1 , wherein the second lens unit comprises two or more lens sub-units that move along mutually different loci during zooming.
9. A zoom lens comprising in order from an object side to an image side: a first lens unit having a positive refractive power that does not move for zooming; a second lens unit having a negative refractive power that moves during zooming; a third lens unit having a positive refractive power that moves during zooming; a fourth lens unit having a positive refractive power that moves during zooming; and a fifth lens unit, in which an interval between each pair of all of the first lens unit, the second lens unit, the third lens unit, the fourth lens unit, and the fifth lens unit is changed during zooming, wherein
the third lens unit moves during zooming along a locus having a zoom position at which a distance between a surface closest to the image side of the first lens unit and a surface closest to the object side of the third lens unit on an optical axis is longer than that at a wide angle end, and
the zoom lens satisfies the following conditions:
1.0< Lw/Lt< 10.0,
1.0< Dw/Dt< 100.0, and
−5.0< f 1/ f 2<−0.5,
where Lw and Lt respectively represent distances between the surface closest to the image side of the first lens unit and a surface closest to the object side of the fourth lens unit on the optical axis at the wide angle end and a telephoto end, Dw and Dt respectively represent distances between a surface closest to the image side of the third lens unit and the surface closest to the object side of the fourth lens unit on the optical axis at the wide angle end and the telephoto end, and f1 and f2 respectively represent focal lengths of the first lens unit and the second lens unit.
10. A zoom lens according to claim 9 , wherein the following conditions are satisfied:
0.1< fw/f 1<1.5 and
2.0< ft/fw< 30.0,
where fw and ft respectively represent focal lengths of the zoom lens at the wide angle end and the telephoto end.
11. A zoom lens according to claim 9 , wherein the following condition is satisfied:
0.1< f 3/ f 4<5.0,
where f3 represents a focal length of the third lens unit, and f4 represents a focal length of the fourth lens unit.
12. A zoom lens according to claim 9 , wherein the following condition is satisfied:
0.0<( M max− Mw )/ Mw< 1.0,
where Mw and Mmax respectively represent ones of a first distance between the surface closest to the image side of the first lens unit and the surface closest to the object side of the third lens unit on the optical axis at the wide angle end and a zoom position at which the first distance is longest.
13. A zoom lens according to claim 9 , further comprising an aperture stop arranged between the second lens unit and the third lens unit or between the third lens unit and the fourth lens unit.
14. A zoom lens according to claim 13 , wherein the aperture stop does not move for zooming.
15. A zoom lens according to claim 9 , wherein the third lens unit is composed of one lens.
16. A zoom lens according to claim 9 , wherein the fourth lens unit is composed of one lens having a positive refractive power and one lens having a negative refractive power.
17. A zoom lens according to claim 9 , wherein the fifth lens unit does not move for zooming.
18. An image pickup apparatus comprising:
a zoom lens; and
an image pickup element that receives light of an image formed by the zoom lens,
the zoom lens comprising in order from an object side to an image side: a first lens unit having a positive refractive power; a second lens unit; a third lens unit having a positive refractive power; a fourth lens unit having a positive refractive power; and a rear lens unit including at least one lens unit, wherein
the second lens unit includes one or more lens sub-units, and has a negative refractive power as a whole,
the first lens unit does not move for zooming, the second lens unit moves during zooming, the fourth lens unit moves during zooming,
the zoom lens includes a stop between the second lens unit and the third lens unit or between the third lens unit and the fourth lens unit, and
the zoom lens satisfies the following expressions:
0.50<( ft ×β2 w 2 )/( fw ×β2 t 2 )<1.40 and
−2.45< f 1/ f 2<−0.50,
where β2w and β2t respectively represent lateral magnifications of the second lens unit at a wide angle end and a telephoto end when a light beam enters from infinity, fw and ft respectively represent focal lengths of the zoom lens at the wide angle end and the telephoto end, f1 represents a focal length of the first lens unit, and f2 represents a focal length of the second lens unit at the wide angle end.
19. An image pickup apparatus comprising:
a zoom lens; and
an image pickup element that receives light of an image formed by the zoom lens,
the zoom lens comprising in order from an object side to an image side: a first lens unit having a positive refractive power that does not move for zooming; a second lens unit having a negative refractive power that moves during zooming; a third lens unit having a positive refractive power that moves during zooming; a fourth lens unit having a positive refractive power that moves during zooming; and a fifth lens unit, in which an interval between each pair of all of the first lens unit, the second lens unit, the third lens unit, the fourth lens unit, and the fifth lens unit is changed during zooming, wherein
the third lens unit moves during zooming along a locus having a zoom position at which a distance between a surface closest to the image side of the first lens unit and a surface closest to the object side of the third lens unit on an optical axis is longer than that at a wide angle end, and
the zoom lens satisfies the following conditions:
1.0< Lw/Lt< 10.0,
1.0< Dw/Dt< 100.0, and
−5.0< f 1/ f 2<−0.5,
where Lw and Lt respectively represent distances between the surface closest to the image side of the first lens unit and a surface closest to the object side of the fourth lens unit on the optical axis at the wide angle end and a telephoto end, Dw and Dt respectively represent distances between a surface closest to the image side of the third lens unit and the surface closest to the object side of the fourth lens unit on the optical axis at the wide angle end and the telephoto end, and f1 and f2 respectively represent focal lengths of the first lens unit and the second lens unit.